This is a special Doctor Who scene written exclusively for BBC Children in Need and is a humorous encounter between the Tenth Doctor and the Fifth Doctor. It stars just David Tennant and Peter Davison.

 Freema Agyeman appears, uncredited, as Martha Jones in footage from "Last of the Time Lords"at the start of the episode, adding to the established events depicted then.

 The striped trousers Peter Davison wears in this special episode are actually the ones especially altered for Colin Baker's Sixth Doctor for his post-regeneration scenes in "The Caves of Androzani".

 On the date of filming, Peter Davison - still the current record holder for the youngest actor to play The Doctor (being only 29 years old when he took over from Tom Baker at the end of the 1981 story "Logopolis") - was older (at the age of 56) than William Hartnell was when he began his run as the First Doctor.

 The aged appearance of the Fifth Doctor was explained away as an effect of the merge.

 Both Peter Davison and David Tennant have already appeared in a Children In Need adventure. David joined Billie Piper for a special scene set straight after "The Parting Of The Ways" back in 2005, whilst Peter featured in the 3-D EastEnders crossover episode "Dimensions In Time" in 1993.

 The Doctor has met different incarnations of himself in three stories: "The Three Doctors" (1973), "The Five Doctors" (1983) and "The Two Doctors" (1985). The Children in Need special "Dimensions in Time" (1993) also featured all the five surviving Doctors at the time. In the Comic Relief sketch "Doctor Who and the Curse of Fatal Death" (1999), also written by Steven Moffat, The Doctor regenerated four times, resulting in five different actors playing the role.

 This short scene, within the Console Room, is set between the end of the Season 29 (New Series 3) episode "Last of the Time Lords" and the 2007 Christmas special "Voyage of the Damned".